Loving thyself can be great for your career—or toxic for your health. It all depends on where you fall on the egocentrism spectrum.

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It was labeled "The Gwyneth Complex" by Psychology Today in a cover story tagged "The Trouble With Celebrity Narcissism." And if you Google "Gwyneth Paltrow narcissist," you will get at least 352,000 results. But there are other self-absorbed titans in our midst. Kanye West's new album is unironically titled Yeezus, while Justin Bieber said he hoped that Holocaust diarist Anne Frank would have been a Belieber had she survived. Narcissism (definition: "inordinate fascination with oneself") could also be called the Zuckerberg or Trump or Jay-Z Complex (though even he might be trumped by Beyoncé, who recently said, "I'm more powerful than my mind can even digest and understand"). But here's the thing: All these perpetrators of egocentrism are hypersuccessful. So for a guy trying to navigate a Wall Street trading floor or the open-plan free-for-all of a Silicon Valley start-up, just how important is it to have an outsize sense of self-importance?

"Narcissism is a key predictor of people who have the drive and ambition to become leaders," says W. Keith Campbell, a psychologist at the University of Georgia. There's one major handicap to self-centeredness. Research shows that me-first behavior can cause a long-term spike in the stress hormone cortisol, which is known to increase the risk of heart attacks and strokes in men. And there's this: A lot of people might think you're a jerk.

The solution? Become the new, savvy egotist—cash in on the positive perks while dodging the destructive consequences. "Narcissism gives you great skills at networking and the aggression you need to be a success," Campbell says. Find out where you fall on the narcissism spectrum, then figure out whether you need a self-esteem boost or a large slice of humble pie.

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Measure Your Ego
There are seven traits of narcissism, and the Narcissistic Personality Inventory test (adapted below) measures all of them. Decide which statements most accurately define you, then check your ego using the key.

1. AUTHORITY
A. I have a natural talent for influencing people.
B. I am not good at influencing people.

2. SELF-SUFFICIENCY
A. I rarely depend on anyone else.
B. I sometimes depend on other people to get things done.

3. SUPERIORITY
A. I think I am a special person.
B. I am no better or worse than most people.

4. EXHIBITIONISM
A. I would do almost anything on a dare.
B. I tend to be a fairly cautious person.

5. EXPLOITATIVENESS
A. I can usually talk my way out of anything.
B. I try to accept the consequences of my behavior.

6. VANITY
A. I don't particularly like to show off my body.
B. I like to show off my body.

7. ENTITLEMENT
A. The thought of ruling the world frightens the hell out of me.
B. If I ruled the world, it would be a better place.

KeyIf you chose "A" on 1, 2, or 3, you score high on the positive narcissism traits of authority, self-sufficiency, and superiority. If you chose "A" on 4 or 5, or "B" on 6 or 7, you score high on vanity, exhibitionism, exploitativeness, and entitlement (unhealthy characteristics that are tied to early death).